Turbo compressor and turbo refrigerator

ABSTRACT

Provided is a turbo compressor configured to compress a gas in cooperation with a rotatable impeller and a diffuser formed around the impeller and to discharge the compressed gas to the outside thereof through a scroll chamber communicating with the diffuser, the turbo compressor including: an impeller casing which is formed by integrally molding a body portion surrounding the impeller and forming a part of a the scroll chamber and a partition plate provided at the rear surface side of the impeller; and a shroud cover which is provided at the inside of the body portion to surround the impeller and forming the scroll chamber in cooperation with the body portion.

TECHNICAL FIELD

1. Field of the Invention

The present invention relates to a turbo compressor and a turbo refrigerator.

Priority is claimed on Japanese Patent Application No. 2010-51929, filed Mar. 9, 2010, the content of which is incorporated herein by reference.

2. Background Art

As a refrigerator cooling or freezing a cooling object such as water, there is known a turbo refrigerator including a turbo compressor compressing and discharging a refrigerant gas. In the turbo compressor included in the turbo refrigerator, for example, as shown in JP-A-2009-185713, the refrigerant gas is compressed in cooperation with a rotatable impeller and a diffuser formed around the impeller. Further, the turbo compressor discharges the compressed refrigerant gas to the outside thereof through a scroll chamber communicating with the diffuser. The diffuser and the scroll chamber are formed by an impeller casing surrounding the impeller.

The impeller casing is generally manufactured by sand mold casting. In sand mold casting, sand for casting needs to be removed after casting from the inside of the scroll chamber. In the impeller casing, a casing body portion forming a part of the scroll chamber is molded separately from a partition plate provided at the rear surface side of the impeller and forming the scroll chamber in cooperation with the body portion. Accordingly, the sand for casting may be removed from the inside of the scroll chamber through the installation position of the partition plate. However, when the casing body portion and the partition plate are molded as separate members, the number of components forming the impeller casing increases, and a process of assembling the partition plate to the casing body portion is required. As a result, there are problems in that the effort and costs of manufacturing the impeller casing increase and effort and costs of manufacturing the turbo compressor and the turbo refrigerator increase.

The invention has been made in view of such circumstances, and an object thereof is to provide a turbo compressor capable of reducing manufacturing effort and manufacturing costs and a turbo refrigerator having the turbo compressor.

SUMMARY OF THE INVENTION

In order to solve the above-described problems, the invention adopts the following configurations.

According to an aspect of the invention, there is provided a turbo compressor configured to compress a gas in cooperation with a rotatable impeller and a diffuser formed around the impeller and discharge the compressed gas to the outside thereof through a scroll chamber communicating with the diffuser, the turbo compressor including: an impeller casing which is formed by integrally molding a body portion surrounding the impeller and forming a part of a the scroll chamber and a partition plate provided at the rear surface side of the impeller; and a shroud cover which is provided at the inside of the body portion to surround the impeller and forms the scroll chamber in cooperation with the body portion.

The scroll chamber of the turbo compressor according to the aspect of the invention is formed by the shroud cover and the body portion of the impeller casing. Accordingly, when the impeller casing is manufactured by sand mold casting, sand for casting inside the scroll chamber may be removed through the installation position of the shroud cover.

Further, the impeller casing of the aspect of the invention is formed by integrally molding the body portion and the partition plate. That is, the body portion and the partition plate are integrally molded, and a process of assembling the partition plate to the body portion is not necessary. As a result, the effort and costs of manufacturing the impeller casing are reduced.

Further, in the turbo compressor according to the aspect of the invention, the body portion may include an inner peripheral surface contacting the shroud cover, and the shroud cover may include an annular fitting frame portion fitted to the inner peripheral surface, an annular shroud portion provided at the inside of the fitting frame portion with a predetermined gap between the shroud portion and the impeller, and a partition plate facing portion connecting the fitting frame portion and the shroud portion to each other and forming the diffuser in cooperation with the partition plate.

Further, in the turbo compressor according to the aspect of the invention, at least a part of the fitting frame may be closely fitted to the inner peripheral surface.

Further, in the turbo compressor according to the aspect of the invention, the shroud cover may include a plurality of reinforcement portions connecting the fitting frame portion and the shroud portion to each other and extending in the radial direction of the shroud portion.

Further, the turbo compressor according to the aspect of the invention may further include an adjustment portion which adjusts the position of the shroud cover with respect to the impeller casing in the rotation axis direction of the impeller.

Further, in the turbo compressor according to the aspect of the invention, the inner peripheral surface of the scroll chamber may be formed by a part of the outer peripheral surface of the shroud cover and a part of the inner peripheral surface of the body portion, and the inner peripheral surface portion of the scroll chamber formed by the outer peripheral surface of the shroud cover may be disposed closer to the rotation shaft of the impeller than the inner peripheral surface portion of the scroll chamber formed by the inner peripheral surface of the body portion, and protrude toward the diffuser along the inner peripheral surface of the scroll chamber.

Further, in the turbo compressor according to the aspect of the invention, the shroud cover may further include a suction port suctioning a gas toward the impeller, and the shroud cover may be inserted from the suction port into the body portion, and be fixed to the body portion at the side of the suction port.

Further, in the turbo compressor according to the aspect of the invention, the diffuser may be formed by the impeller casing and the shroud cover.

Further, according to another aspect of the invention, there is provided a turbo refrigerator including: a condenser which cools and liquefies a compressed refrigerant; an evaporator which evaporates the liquefied refrigerant and takes evaporation heat from a cooling object to cool the cooling object; and a compressor which compresses the refrigerant evaporated from the evaporator and supplies the compressed refrigerant to the condenser, wherein the above-described turbo compressor may be used as the compressor.

According to the aspect of the invention, the following advantages may be obtained.

According to the aspect of the invention, the effort and costs of manufacturing the impeller casing may be reduced. As a result, there is an advantage that the manufacturing effort and the manufacturing costs may be reduced in the turbo compressor and the turbo refrigerator having the turbo compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a schematic configuration of a turbo refrigerator of an embodiment of the invention.

FIG. 2 is a horizontal cross-sectional view illustrating the turbo compressor of the embodiment of the invention.

FIG. 3 is a horizontal cross-sectional view illustrating a compressor unit of the embodiment of the invention.

FIG. 4 is a horizontal cross-sectional view illustrating a first compression stage of the embodiment of the invention.

FIG. 5 is a front view illustrating a shroud cover of the embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, an exemplary embodiment of the invention will be described by referring to FIGS. 1 to 5. In the respective drawings used for the following description, the scales of the respective members are appropriately changed so that the respective members have recognizable sizes.

FIG. 1 is a block diagram illustrating a schematic configuration of a turbo refrigerator S1 of the embodiment. The turbo refrigerator S1 of the embodiment is installed at, for example, a building, a factory, or the like in order to generate air-conditioning cooling water. As shown in FIG. 1, the turbo refrigerator S1 includes a condenser 1, an economizer 2, an evaporator 3, and a turbo compressor 4.

A compressed refrigerant gas X1 as a compressed gas refrigerant is supplied to the condenser 1, and the compressed refrigerant gas X1 is cooled and liquefied at the condenser 1 so that it becomes a refrigerant liquid X2. Further, as shown in FIG. 1, the condenser 1 is connected to the turbo compressor 4 through a passageway R1 where the compressed refrigerant gas X1 flows, and is connected to the economizer 2 through a passageway R2 where the refrigerant liquid X2 flows. An expansion valve 5 is installed in the passageway R2 so as to depressurize the refrigerant liquid X2.

The economizer 2 temporarily stores the refrigerant liquid X2 depressurized at the expansion valve 5. The economizer 2 is connected to the evaporator 3 through a passageway R3 where the refrigerant liquid X2 flows, and is connected to the turbo compressor 4 through a passageway R4 where a gas phase component X3 of the refrigerant generated in the economizer 2 flows. An expansion valve 6 is installed at the passageway R3 so as to further depressurize the refrigerant liquid X2. Further, the passageway R4 is connected to the turbo compressor 4 so as to supply the gas phase component X3 to a second compression stage 22 described later and provided in the turbo compressor 4.

The evaporator 3 cools a cooling object by taking evaporation heat from the cooling object such as water in a manner such that the refrigerant liquid X2 evaporates. The evaporator 3 is connected to the turbo compressor 4 through a passageway R5 where a refrigerant gas X4 generated by the evaporation of the refrigerant liquid X2 flows. The passageway R5 is connected to a first compression stage 21 described later and provided in the turbo compressor 4.

The turbo compressor 4 compresses the refrigerant gas X4 so that it becomes the compressed refrigerant gas X1. As described above, the turbo compressor 4 is connected to the condenser 1 through the passageway R1 where the compressed refrigerant gas X1 flows, and is connected to the evaporator 3 through the passageway R5 where the refrigerant gas X4 flows.

In the turbo refrigerator S1 having the above-described configuration, the compressed refrigerant gas X1 supplied to the condenser 1 through the passageway R1 is cooled and liquefied by the condenser 1 so that it becomes the refrigerant liquid X2.

The refrigerant liquid X2 is depressurized by the expansion valve 5 when it is supplied to the economizer 2 through the passageway R2, is temporarily stored in a depressurized state in the economizer 2, and is further depressurized by the expansion valve 6 when it is supplied to the evaporator 3 through the passageway R3. That is, the twice depressurized refrigerant liquid X2 is supplied to the evaporator 3.

The refrigerant liquid X2 supplied to the evaporator 3 is evaporated by the evaporator 3 so that it becomes the refrigerant gas X4, and is supplied to the turbo compressor 4 through the passageway R5.

The refrigerant gas X4 supplied to the turbo compressor 4 is compressed by the turbo compressor 4 so that it becomes the compressed refrigerant gas X1, and is supplied again to the condenser 1 through the passageway R1.

The gas phase component X3 of the refrigerant generated when the refrigerant liquid X2 is stored in the economizer 2 is supplied to the turbo compressor 4 through the passageway R4, and is compressed together with the refrigerant gas X4 so that it is supplied as the compressed refrigerant gas X1 to the condenser 1 through the passageway R1. In the turbo refrigerator S1, the cooling object is cooled or frozen in a manner such that the refrigerant liquid X2 takes evaporation heat from the cooling object when evaporating from the evaporator 3.

Next, the turbo compressor 4 as a characteristic portion of the embodiment will be more specifically described.

FIG. 2 is a horizontal cross-sectional view illustrating the turbo compressor 4 of the embodiment. FIG. 3 is a horizontal cross-sectional view illustrating a compressor unit 20 of the embodiment. FIG. 4 is a horizontal cross-sectional view illustrating the first compression stage 21 of the embodiment. Further, FIG. 5 is a front view illustrating a shroud cover of the embodiment. In FIG. 4, the description of an inlet guide vane 21 f and a drive mechanism 21 g is omitted, and a first impeller 21 a and a rotation shaft 23 are represented by an imaginary line.

As shown in FIG. 2, the turbo compressor 4 of the embodiment includes a motor unit 10, a compressor unit 20, and a gear unit 30.

The motor unit 10 includes a motor 12 which includes an output shaft 11 and serves as a drive source driving the compressor unit 20, and a motor casing 13 which surrounds the motor 12 and in which the motor 12 is installed. The drive unit driving the compressor unit 20 is not limited to the motor 12. For example, an internal combustion engine may be used.

The output shaft 11 of the motor 12 is rotatably supported by a first bearing 14 and a second bearing 15 fixed to the motor casing 13.

The compressor unit 20 includes the first compression stage 21 which suctions and compresses the refrigerant gas X4 (refer to FIG. 1), and the second compression stage 22 which further compresses the refrigerant gas X4 compressed at the first compression stage 21 and discharges it as the compressed refrigerant gas X1 (refer to FIG. 1).

As shown in FIG. 3, the first compression stage 21 includes a first impeller 21 a (an impeller) which discharges the refrigerant gas X4 in the radial direction by applying velocity energy to the refrigerant gas X4 supplied in the thrust direction, a first diffuser 21 b (a diffuser) which compresses the refrigerant gas X4 by converting the velocity energy applied to the refrigerant gas X4 into pressure energy by the first impeller 21 a, a first scroll chamber 21 c (a scroll chamber) which derives the refrigerant gas X4 compressed by the first diffuser 21 b to the outside of the first compression stage 21, and a suction port 21 d which supplies the refrigerant gas X4 to the first impeller 21 a by suctioning the refrigerant gas X4.

A part of the first diffuser 21 b, the first scroll chamber 21 c, and the suction port 21 d is formed by a first impeller casing 21 e surrounding the first impeller 21 a. The first impeller casing 21 e and the first scroll chamber 21 c will be described later in detail.

The rotation shaft 23 is provided inside the compressor unit 20 so as to extend across the first compression stage 21 and the second compression stage 22. The first impeller 21 a is fixed to the rotation shaft 23, and the rotation shaft 23 rotates when a rotation force is transmitted from the motor 12 (refer to FIG. 2) to the rotation shaft 23.

Further, a plurality of inlet guide vanes 21 f is provided in the suction port 21 d of the first compression stage 21 so as to adjust the suction amount of the first compression stage 21. Each inlet guide vane 21 f is rotatably supported by the drive mechanism 21 g fixed to the first impeller casing 21 e so that an external area in the stream direction of the refrigerant gas X4 is changeable. Further, a vane drive unit 24 (refer to FIG. 2) is installed at the outside of the first impeller casing 21 e so that the vane drive unit 24 is connected to the drive mechanism 21 g and rotationally drives each inlet guide vane 21 f.

The second compression stage 22 includes a second impeller 22 a which discharges the refrigerant gas X4 in the radial direction by applying velocity energy to the refrigerant gas X4 compressed at the first compression stage 21 and supplied in the thrust direction, a second diffuser 22 b which compresses and discharges the compressed refrigerant gas X1 by converting the velocity energy applied to the refrigerant gas X4 into pressure energy by the second impeller 22 a, a second scroll chamber 22 c which derives the compressed refrigerant gas X1 discharged from the second diffuser 22 b to the outside of the second compression stage 22, and an introduction scroll chamber 22 d which guides the refrigerant gas X4 compressed by the first compression stage 21 to the second impeller 22 a.

The second diffuser 22 b, the second scroll chamber 22 c, and the introduction scroll chamber 22 d are formed by a second impeller casing 22 e surrounding the second impeller 22 a.

The second impeller 22 a is fixed to the rotation shaft 23 so that the rear surface thereof is coupled to the rear surface of the first impeller 21 a, and rotates when a rotation force is transmitted from the motor 12 to the rotation shaft 23.

The second scroll chamber 22 c is connected to the passageway R1 (refer to FIG. 1) supplying the compressed refrigerant gas X1 to the condenser 1, and supplies the compressed refrigerant gas X1 derived from the second compression stage 22 to the passageway R1.

The first scroll chamber 21 c of the first compression stage 21 and the introduction scroll chamber 22 d of the second compression stage 22 are connected to each other through an external pipe (not shown) that is provided separately from the first compression stage 21 and the second compression stage 22. The refrigerant gas X4 compressed at the first compression stage 21 is supplied to the second compression stage 22 through an external pipe. The passageway R4 (refer to FIG. 1) is connected to the external pipe, and the gas phase component X3 of the refrigerant generated in the economizer 2 is configured to be supplied to the second compression stage 22 through the external pipe.

The rotation shaft 23 is rotatably supported by a third bearing 26 fixed to the second impeller casing 22 e at a space 25 between the first compression stage 21 and the second compression stage 22 and a fourth bearing 27 (refer to FIG. 2) fixed to the gear unit 30 of the second impeller casing 22 e. The rotation shaft 23 is provided with a labyrinth seal 23 a that prevents the refrigerant gas X4 from flowing from the introduction scroll chamber 22 d to the gear unit 30.

The configuration of the first impeller casing 21 e and the first scroll chamber 21 c will be described in detail. As shown in FIG. 4, a shroud cover 28 is provided in the first impeller casing 21 e of the first compression stage 21.

The first impeller casing 21 e is formed by integrally molding a casing body portion 21 h (a body portion) surrounding the first impeller 21 a and forming a part of the first scroll chamber 21 c and a partition plate 21 i provided at the rear surface side of the first impeller 21 a. The first impeller casing 21 e is molded by sand mold casting.

The casing body portion 21 h is molded in an annular shape surrounding the first impeller 21 a, and includes an inner peripheral surface 21 j contacting the shroud cover 28. The inner peripheral surface 21 j is molded so as to have a circular shape when seen from the side of the suction port 21 d. The partition plate 21 i is molded in an annular plate shape, and is disposed between the installed position of the first impeller 21 a and the space 25. The center portion of the partition plate 21 i is provided with a second labyrinth seal 29 which surrounds the rotation shaft 23 and prevents the refrigerant gas X4 from flowing from the first impeller 21 a to the space 25.

The first scroll chamber 21 c is formed by the outer peripheral surface of the shroud cover 28 and the inner peripheral surface of the casing body portion 21 h. More specifically, a part of an outer peripheral surface of a fitting frame portion 28 a of the shroud cover 28 forms a part of the inner peripheral surface of the first scroll chamber 21 c (that is, in the inner peripheral surface, a portion located at the inner diameter side of the first compression stage 21). Further, a part of the inner peripheral surface of the casing body portion 21 h forms a part of the inner peripheral surface of the first scroll chamber 21 c (that is, in the inner peripheral surface, a concave portion located at the outer diameter side of the first compression stage 21). Further, the fitting frame portion 28 a is disposed closer to the rotation shaft 23 than a part of the inner peripheral surface of the first scroll chamber 21 c formed by the inner peripheral surface of the casing body portion 21 h, and protrudes toward the diffuser along the inner peripheral surface of the first scroll chamber 21.

As described above, the shroud cover 28 is provided at the inside of the casing body portion 21 h so as to surround the first impeller 21 a, and forms the first scroll chamber 21 c in cooperation with the casing body portion 21 h.

More specifically, the shroud cover 28 is formed by integrally molding an annular fitting frame portion 28 a which is fitted to the inner peripheral surface 21 j, an annular shroud portion 28 b which is provided at the inside of the fitting frame portion 28 a with a predetermined gap between the annular shroud portion 28 b and the first impeller 21 a, and a partition plate facing portion 28 c which connects the fitting frame portion 28 a and the shroud portion 28 b to each other and forms the first diffuser 21 b in cooperation with the partition plate 21 i.

The fitting frame portion 28 a and the shroud portion 28 b are formed in a substantially cylindrical shape, and the partition plate facing portion 28 c is formed in an annular plate shape. Accordingly, the weight of the shroud cover 28 may be decreased.

A part of the outer peripheral surface of the fitting frame portion 28 a is closely fitted to the inner peripheral surface 21 j. Accordingly, the refrigerant gas X4 may be prevented and suppressed from flowing from the first scroll chamber 21 c through the fitting portion between the fitting frame portion 28 a and the inner peripheral surface 21 j. Further, a force necessary for fitting the shroud cover 28 to the inner peripheral surface 21 j may be reduced.

The shroud cover 28 is fixed to the casing body portion 21 h at a fixation portion 28 d (an adjustment portion). More specifically, the shroud cover 28 is inserted from the suction port 21 d (that is, the inner peripheral surface 21 j) into the casing body portion 21 h, and is fixed from the suction port 21 d to the casing body portion 21 h at the fixation portion 28 d (the adjustment portion). Further, the fitting frame portion 28 a at the fixation portion 28 d is provided with a flange portion 28 e that is used for the connection to the casing body portion 21 h. The flange portion 28 e is formed in an annular frame shape that protrudes outward in the radial direction from the end portion at the side of the suction port 21 d in the fitting frame portion 28 a. The shroud cover 28 is fixed to the casing body portion 21 h by using a plurality of bolts 28 f penetrating the flange portion 28 e in the axis direction of the rotation shaft 23.

Further, the fixation portion 28 d is also used as an adjustment portion that adjusts the position of the shroud cover 28 with respect to the first impeller casing 21 e in the rotation axis direction of the first impeller 21 a. Specifically, when a predetermined thin metal plate 29 (a so-called shim) is interposed between the flange portion 28 e and the casing body portion 21 h, and the thickness, the number or the like of the thin metal plates 29 is adjusted, the position of the shroud cover 28 may be adjusted in the rotation axis direction of the first impeller 21 a. Since the position of the shroud cover 28 is adjusted, a gap between the shroud portion 28 b and the first impeller 21 a may be optimally adjusted, and the safe rotation of the first impeller 21 a and the high compression efficiency of the first compression stage 21 may be ensured.

As shown in FIGS. 4 and 5, the shroud cover 28 includes a plurality of ribs 28 g (reinforcement portions) which connects the fitting frame portion 28 a and the shroud portion 28 b to each other and extends in the radial direction of the shroud portion 28 b. The shroud cover 28 is molded by, for example, casting, but the surfaces of the shroud portion 28 b and the partition plate facing portion 28 c at the side of the first impeller 21 a are subjected to machining (cutting or the like) after the casting. Since the plurality of ribs 28 g is provided, the strength of the shroud portion 28 b and the partition plate facing portion 28 c improves. As a result, vibration or the like may be prevented during the machining.

The method of manufacturing the first impeller casing 21 e will be described.

As described above, the first impeller casing 21 e is molded by sand mold casting. In the sand mold casting, it is necessary to remove sand for casting from the inside of the first scroll chamber 21 c after the casting. Since the first scroll chamber 21 c of the embodiment is formed by the casing body portion 21 h and the shroud cover 28, sand for casing inside the first scroll chamber 21 c may be removed through the installation position of the shroud cover 28.

Further, the first impeller casing 21 e of the embodiment is formed by integrally molding the casing body portion 21 h and the partition plate 21 i. That is, since the casing body portion 21 h and the partition plate 21 i are integrally molded, it is not necessary to provide a process of assembling the partition plate 21 i to the casing body portion 21 h, and to reduce the effort and costs of manufacturing the first impeller casing 21 e.

A plurality of types of the shroud covers 28 may be provided in accordance with the size, the shape, or the like of the first impeller 21 a.

In the turbo refrigerator S1 (refer to FIG. 1) including the turbo compressor 4, in order to ensure a predetermined cooling capability, the size or shape of the first impeller 21 a, or the width or the like of the first diffuser 21 b may be changed. In the embodiment, since a plurality of types of shroud covers 28 is provided in accordance with the size or shape of the first impeller 21 a, or the width or the like of the first diffuser 21 b, a predetermined cooling capability in the turbo refrigerator S1 may be ensured.

Next, a configuration ensuring the predetermined cooling capability will be described by referring to FIG. 2. The gear unit 30 is used to transmit the rotation force of the motor 12 to the rotation shaft 23, and includes a spur gear 31 which is fixed to the output shaft 11, a pinion gear 32 which is fixed to the rotation shaft 23 and meshes with the spur gear 31, and a gear casing 33 which accommodates the spur gear 31 and the pinion gear 32.

The spur gear 31 has an outer diameter larger than that of the pinion gear 32, and transmits the rotation force of the motor 12 to the rotation shaft 23 so that the rpm of the rotation shaft 23 increases with respect to the rpm of the output shaft 11 by the corporation between the spur gear 31 and the pinion gear 32. This transmission method is not limited, and the diameters of the plurality of gears may be set so that the rpm of the rotation shaft 23 is equal to or lower than the rpm of the output shaft 11.

In the gear casing 33, the motor casing 13 and the second impeller casing 22 e are separately molded, and are connected to each other. The interior of the gear casing 33 is provided with an accommodation space 33 a that accommodates the spur gear 31 and the pinion gear 32. Further, the gear casing 33 is provided with an oil tank 34 that collects and stores a lubricant supplied to a sliding portion of the turbo compressor 4.

Next, an operation of the turbo compressor 4 of the embodiment will be described.

First, a rotation force of the motor 12 is transmitted to the rotation shaft 23 through the spur gear 31 and the pinion gear 32, so that the first impeller 21 a and the second impeller 22 a of the compressor unit 20 are rotationally driven.

When the first impeller 21 a is rotationally driven, the suction port 21 d of the first compression stage 21 enters a negative pressure state, the refrigerant gas X4 flows from the passageway R5 to the first compression stage 21 through the suction port 21 d.

The refrigerant gas X4 flowing into the first compression stage 21 flows into the first impeller 21 a in the thrust direction, and is discharged in the radial direction by applying velocity energy thereto using the first impeller 21 a.

The refrigerant gas X4 discharged from the first impeller 21 a is compressed by converting the velocity energy into pressure energy using the first diffuser 21 b.

The refrigerant gas X4 discharged from the first diffuser 21 b is derived to the outside of the first compression stage 21 through the first scroll chamber 21 c. The refrigerant gas X4 derived to the outside of the first compression stage 21 is supplied to the second compression stage 22 through an external pipe (not shown).

The refrigerant gas X4 supplied to the second compression stage 22 flows into the second impeller 22 a in the thrust direction through the introduction scroll chamber 22 d, and is discharged in the radial direction by applying velocity energy thereto using the second impeller 22 a.

The refrigerant gas X4 discharged from the second impeller 22 a is further compressed into the compressed refrigerant gas X1 by converting the velocity energy into pressure energy using the second diffuser 22 b.

The compressed refrigerant gas X1 discharged from the second diffuser 22 b is derived to the outside of the second compression stage 22 through the second scroll chamber 22 c. The compressed refrigerant gas X1 derived to the outside of the second compression stage 22 is supplied to the condenser 1 through the passageway R1.

Finally, the operation of the turbo compressor 4 is finished.

Therefore, according to the embodiment, the following advantages may be obtained.

According to the embodiment, since the casing body portion 21 h and the partition plate 21 i are integrally molded, it is not necessary to provide a process of assembling the partition plate 21 i to the casing body portion 21 h. As a result, the effort and costs of manufacturing the first impeller casing 21 e may be reduced. Furthermore, there is an advantage in that the effort and costs of manufacturing the turbo compressor 4 and the turbo refrigerator S1 may be reduced.

While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. In the above-described examples, additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.

For example, the turbo compressor 4 of the above-described embodiment is the double-stage compression type turbo compressor including the first compression stage 21 and the second compression stage 22, but the invention is not limited thereto. For example, a single-stage compression type or a multiple-stage compression type such as triple or more compression types may be adopted. Further, the turbo compressor 4 of the above-described embodiment is used in the turbo refrigerator S1, but may be used as, for example, a supercharger supplying compressed air to an internal combustion engine. 

1. A turbo compressor configured to compress a gas in cooperation with a rotatable impeller and a diffuser formed around the impeller and to discharge the compressed gas the outside thereof through a scroll chamber communicating with the diffuser, the turbo compressor comprising: an impeller casing which is formed by integrally molding a body portion surrounding the impeller and forms a part of a the scroll chamber and a partition plate provided at the rear surface side of the impeller; and a shroud cover which is provided at the inside of the body portion to surround the impeller and forming the scroll chamber in cooperation with the body portion.
 2. The turbo compressor according to claim 1, wherein the body portion includes an inner peripheral surface contacting the shroud cover, and wherein the shroud cover includes an annular fitting frame portion fitted to the inner peripheral surface, an annular shroud portion provided at the inside of the fitting frame portion with a predetermined gap between the shroud portion and the impeller, and a partition plate facing portion connecting the fitting frame portion and the shroud portion to each other and forming the diffuser in cooperation with the partition plate.
 3. The turbo compressor according to claim 2, wherein at least a part of the fitting frame is closely fitted to the inner peripheral surface.
 4. The turbo compressor according to claim 2, wherein the shroud cover includes a plurality of reinforcement portions connecting the fitting frame portion and the shroud portion to each other and extending in the radial direction of the shroud portion.
 5. The turbo compressor according to claim 1, further comprising: an adjustment portion which adjusts the position of the shroud cover with respect to the impeller casing in the rotation axis direction of the impeller.
 6. The turbo compressor according to claim 2, wherein the inner peripheral surface of the scroll chamber is formed by a part of the outer peripheral surface of the shroud cover and a part of the inner peripheral surface of the body portion, and wherein the inner peripheral surface portion of the scroll chamber formed by the outer peripheral surface of the shroud cover is disposed closer to the rotation shaft of the impeller than the inner peripheral surface portion of the scroll chamber formed by the inner peripheral surface of the casing body portion, and protrudes toward the diffuser along the inner peripheral surface of the scroll chamber.
 7. The turbo compressor according to claim 1, wherein the shroud cover further includes a suction port suctioning a gas toward the impeller, and wherein the shroud cover is inserted from the suction port into the body portion, and is fixed to the body portion at the side of the suction port.
 8. The turbo compressor according to claim 1, wherein the diffuser is formed by the impeller casing and the shroud cover.
 9. A turbo refrigerator comprising: a condenser which cools and liquefies a compressed refrigerant; an evaporator which evaporates the liquefied refrigerant and takes evaporation heat from a cooling object to cool the cooling object; and a compressor which compresses the refrigerant evaporated from the evaporator and supplies the compressed refrigerant to the condenser, wherein the turbo compressor according to claim 1 is used as the compressor. 